Fluid cylinders used in industry are provided with many features of construction and many combinations of parts that adapt the cylinders to particular power and maintenance requirements, to particular applications, and to particular stroke characteristics. As one example, fluid cylinders may be adapted to robotic applications. Fluid cylinders may, as an example, be mounted on fixtures stationed along assembly lines so that their pistons stroke in many different directions to orchestrate various tasks. For these applications, the cylinders are controlled by computers, utilizing feedback signals from sensor devices mounted on the cylinders.